Fertilisation to Trilaminar 🗸

Question 1

Fertilisation

Answer 1

union of gametes, fusion of sperm and oocyte to form a zygote

Question 2

Where does fertilisation take place?

Answer 2

ampulla of uterine tube

Question 3

Process of fertilisation

Answer 3

1. Sperm binds to zona pellucida glycoprotein
2. Acrosomal enzymes released from sperm head; sperm digests its way into egg
3. Egg and sperm plasma membranes fuse and sperm contents enters the egg
4. Sperm entry triggers completion of meiosis 2 and release of cortical granules by oocyte (make ZP impenetrable to other sperm)

Question 4

sperm binds to ____ ____ _____

Answer 4

zona pellucida glycoprotein

Question 5

_____ _____ released from sperm head, sperm digests its way into the egg

Answer 5

acrosomal enzymes

Question 6

egg and sperm plasma membranes fuse and _____ _____ _____ _____ _____

Answer 6

sperm contents enter the egg

Question 7

sperm entry triggers completion of _____ __ and release of _____ _____ by oocyte (makes soma pellucida impenetrable to other sperm)

Answer 7

meiosis 2, cortical granules

Question 8

The cells are confined within the ZP during cleavage, they change shape, what is this called?

Answer 8

compaction

Question 9

Morula

Answer 9

16+ cells after fertilisation

Question 10

Blastocyst

Answer 10

200-300 cells after fertilisation

Question 11

two cell types in the blastocyst

Answer 11

outer cell mass (trophoblast)
inner cell mass (embryoblast)

Question 12

trophoblast

Answer 12

contacts with the endometrium of the uterus to facilitate implantation and formation of the placenta

Question 13

embryoblast

Answer 13

responsible for the formation of the embryo itself

Question 14

how do cells maximise space in cleavage

Answer 14

come closer into contact with each other

Question 15

which junctions do the cells make in cleavage

Answer 15

inner cells form cell junctions
outer cells form gap junctions

Question 16

fluid in the ZP produces blurred cell mass, what dies this signal?

Answer 16

formation of the blastocyst

Question 17

implantation of the embryo

Answer 17

embryo implants into endometrial lining on anterior or posterior uterine wall

Question 18

ectopic pregnancy

Answer 18

implantation outwith the uterus

Question 19

placenta previa

Answer 19

placenta lies low in the uterus and partially/completely covers the cervix

Question 20

what day does development of the bilaminar embryo take place?

Answer 20

7.5-13

Question 21

Day 7.5

Answer 21

trophoblast divides into cytotrophoblast (individual cells) and syncytioblast (single multinucleated cell which produces hCG)
Embryoblast divides into epiblast (dorsal surface) and hypoblast (ventral surface)
amniotic cavity begins to form

Question 22

day nine

Answer 22

formation of two cavities:
- amniotic cavity (epiblast)
- primitive yolk sac (hypoblast)
implantation is complete

Question 23

day twelve

Answer 23

uteroplacental circulation established
extraembryonic mesoderm develops then degenerates, forming the chorionic cavity

Question 24

day thirteen

Answer 24

further development of chorionic cavity
presence of existing stalk (later the umbilical cord)
second wave of hypoblast cells migrate to form definitive yolk sac

Question 25

Gastrulation (becomes trilaminar)

Answer 25

invagination of the epiblast cells through the primitive stream to form the three primary germ layers (ectoderm, mesoderm and endoderm)

Question 26

Ectoderm

Answer 26

forms the epidermis of the skin, hair and nails forms nervous system

Question 27

types of mesoderm

Answer 27

paraxial, intermediate and lateral plate (which has somatic and visceral layers)

Question 28

paraxial emsoderm

Answer 28

forms axial skeleton and skeletal muscle

Question 29

intermediate mesoderm

Answer 29

forms urogenital systems

Question 30

two layers of lateral plate mesoderm

Answer 30

somatic and visceral

Question 31

somatic layer of the lateral plate mesoderm

Answer 31

forms the dermis, lining of the body wall and parts of limbs

Question 32

visceral layer of the lateral plate mesoderm

Answer 32

forms the cardiovascular system, mesothelial covering of organs and smooth muscle

Question 33

endoderm

Answer 33

forms lining if the gut tube, respiratory tract, bladder and urethra.